The Human Event; or, The Origin of the Human Species; or, The Chimp and the Double Chromosome: The Chromosomal Fusion Ev

Human chromosome 2 was formed in a single chimp by a fusion of chimpanzee chromosomes 2A and 2B. The progeny of this chimp had 46-chromosomes, and could not breed with the rest of the 48-chromosome chimps. As a result, the two evolved separately. The 46-chromosome family became humans, and the 48-chromosome chimps became chimpanzees and bonobos.